electrolytic capacitor questions

[technicolor]

Well, it's not dead anymore, but it is on life support.

The maggie combo, (chassis unknown but closely resembles a 933) showed some signs of life after my first recap, so i'm feeling kind of smart but dangerous at the same time, lol

So here's my question, i know on non electrolytics it has been stated many times, it's ok to replace with a much higher rated voltage, but, is it ok to do that with electrolytics? I replaced a few 200mfd lytics in the radio chassis with much higher rated voltage, 160v instead of 50.

IS this ok?

[zeno]

Originally Posted by technicolor

Well, it's not dead anymore, but it is on life support.

The maggie combo, (chassis unknown but closely resembles a 933) showed some signs of life after my first recap, so i'm feeling kind of smart but dangerous at the same time, lol

So here's my question, i know on non electrolytics it has been stated many times, it's ok to replace with a much higher rated voltage, but, is it ok to do that with electrolytics? I replaced a few 200mfd lytics in the radio chassis with much higher rated voltage, 160v instead of 50.

IS this ok?

Absolutely. Only other consideration is temperature. Only caps in
old sets I remember higher temp is the line cap in a doubler.
Newer sets you gotta watch it more. Cost & physical, size, tolerance,
& mounting also factors.

Higher V better
Higher Temp better
mfd 47 OK for 50, 4.7 OK for 4 etc
mfd can sometimes go a little higher

73 Zeno

[technicolor]

Originally Posted by zeno

Absolutely. Only other consideration is temperature. Only caps in
old sets I remember higher temp is the line cap in a doubler.
Newer sets you gotta watch it more. Cost & physical, size, tolerance,
& mounting also factors.

Higher V better
Higher Temp better
mfd 47 OK for 50, 4.7 OK for 4 etc
mfd can sometimes go a little higher

73 Zeno

I had to sub 3.3mfd for 3.0. Is that within tolerance?

[Rod Beauvex]

Unless I flunked math, .3 is ten percent of 3.0, which is usually standard practice. It varied from part to part, but electrlytics from that era could be half or double their printed value. Resistors could be ten to 20 percent off, five percent occasionally appeared. Smaller, non paper or electrolytic caps, such as ceramics, mylars, and micas could be 10 or 5 percent their stated value.

Given the age of the unit in question, if should be fine. If the original part was 10 %, the new part should be fine. Always check scematics. Usually they say all resistors and/or capacitors are 10% / 20% unless otherwise noted, in which case they are usually noted near the part on the page.

[Tubejunke]

With capacitors you can use ANY higher voltage than what the schematic calls for. Never go by the old part because somebody might have subbed in whatever they had laying around; always check the schematic. As far as the value of capacitance goes, you always go higher; never lower. I believe the percentages listed in other posts on this thread about cover it. Last, always observe polarity with electrolytics or you will likely have fireworks and ruined parts. Polarity is not an issue with other types.

[Rod Beauvex]

Going up in value is ok for B+, but other circuits this is not always ok to do.

[Tubejunke]

Originally Posted by Rod Beauvex

Going up in value is ok for B+, but other circuits this is not always ok to do.

If you are referring to capacitance, then you would be right. However, voltage is unlimited no matter the circuit as long as you meet or exceed the working voltage that the capacitor being replaced was rated at.

Although not always in our possession, a schematic is just as important a tool as any other that we use. Exhibit A: You have a new/old piece of equipment that the same cap keeps going bad. Everything else in the circuit checks out fine, but that one cap is going kaput. Well, in all these decades of existence it is quite possible that a layman replaced the first one without paying attention to the working voltage rating. So what you find you replace based on what is marked on the casing of the wrong part and you have no reference to what in fact is right for that circuit.

Not even Ohms law calculations will bail you out without at least two known circuit values which you may not always be able to deduce without either another known to be working circuit or a schematic.

[wa2ise]

Oh, and be sure that the polarity is correct. If possible, you could put a voltmeter across the cap to see how much voltage and which way is the positive. Maybe the circuit is pumping a fair amount of AC current thru the cap, in which case if the ESR is too high it could get too hot and dry out. A 105C cap may help. And one physically larger may spread out the heating.

[Electronic M]

Polarity only matters for electrolytic capacitors. Micas, and papers don't care which way you connect them.
Ooh and on vintage lytics the metal can is almost always negative.